Mental Floss

Brain Game: Running a 5K


I was always good at math, so I was surprised when I came across this number puzzle and quickly got the wrong answer... but admittedly, I did. Hopefully, you'll do better:

DO THE CALCULATIONS IN YOUR HEAD (no help allowed!) Take 1000 and add 40 to it. Now add another 1000. Now add 30. Add another 1000. Now add 20. Now add another 1000. Now add 10. What is the total?

HERE'S the answer.

THE ANSWER: If you came up with 5000, you stepped into the same trap I did. The correct answer is 4100, which you can verify as necessary.